Optical networks include nodes interconnected by optical links formed by fiber optic cables including various pre-amplifiers, post-amplifiers, and optional intermediate line amplifiers. Various power control techniques are utilized to control optical power through the various amplifiers, over the optical links. With advance coherent modulation and the like, conventional power control techniques for optimization are slow, i.e., operate in seconds, leading to slow capacity changes (i.e., add/delete channels for new demands or restoration). A technique to deal with the control of optical power involves the use of so-called channel holders which can include Amplified Stimulated Emission (ASE) sources, modulated lasers, unmodulated lasers, etc. Channel holders are used in optical links to keep optical spectrum in full-fill loading condition so that any capacity change activity can be digitally handled by switching the channel holders with traffic signals, i.e., there is no need to perform an optimization because any capacity change includes swapping a traffic-bearing channel for a channel holder or vice versa. The conventional approach of swapping channels is limited. For example, one approach is to swap one channel at a time which is inefficient. Assuming 2-4s to add each channel, to add 95× channels on top 1× In-Service (IS) channel, will take around 190-380s per Optical Multiplex Section (OMS).
While channel holders solve the optimization time problem, there is a need to perform capacity changes, i.e., swapping channel holders for traffic-bearing channels without causing too much power transition in a line system, and vice versa, faster than one channel or set of contiguous channels at a time.